Note: Descriptions are shown in the official language in which they were submitted.
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WET WIPES AND METHODS FOR MAKING SAME
FIELD OF THE INVENTION
The present invention relates to wet wipes and more particularly to wet wipes
that
comprise a fibrous structure and a liquid composition that exhibit novel
properties.
BACKGROUND OF THE INVENTION
Various fibrous structures have been used in the past as substrates for wet
wipes. For
example, fibrous structures comprising a mixture of pulp and regenerated
cellulose fibers, such
as rayon and/or lyocell, with or without binding fibers, such as
polypropylene/polyester
bicomponent fibers, are known to be used as substrates for wet wipes. Further,
fibrous structures
comprising 100% pulp fibers are also known to be used as substrates for wet
wipes. Still further
yet, fibrous structures comprising 100% polypropylene fibers are known to be
used as substrates
for wet wipes.
One important property that consumers desire is that wet wipes must be strong
enough to
maintain integrity during use, which is oftentimes 28 days or greater from the
time the wet wipe
is produced. In order to maintain integrity during use, known wet wipes
utilize various
technologies. For example, some wet wipes achieve strength by using
thermoplastic polymers,
such as polypropylene, to form the filaments/fibers of their fibrous
structures and then optionally,
thermal bonding the fibrous structures. Others achieve strength by the process
by which they are
made, for example, hydroentangling (spunlacing). Still others achieve strength
by adding a
polymeric binder to the fibrous structures, for example an acid-insoluble,
alkali-soluble
polycarboxylic acid binder and/or an ion-triggerable polymeric binders and/or
temperature-
sensitive binders and/or pH sensitive binders and/or water-soluble binder such
as polyvinyl
alcohol that are typically applied to the fibrous structure prior to
application of any liquid
composition. In the case of wet wipes that comprise a 100% pulp fiber fibrous
structure, strength
has been achieved by employing a permanent wet strength agent, such as Kymene
, which is
commercially available from Ashland Inc. and/or Parez 631, which is
commercially available
from Kemira Chemicals Inc., during the fibrous structure making process, which
can be a wet-
laid papermaking process.
Another important property that consumers desire is that the wet wipes need to
be
dispersible in order for the consumers to dispose of by flushing in a toilet
and into a sewer
system, such as a publics sewer system, and/or a septic system without
creating clogging issues.
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In order to achieve dispersibility, known wet wipes have utilized wet strength
technologies such
as those described above that may be triggered by some condition that causes
the wet wipe to
break apart into smaller pieces. In addition some wet wipes have used
mechanical weakening to
aid in dispersibility of the wet wipe.
The challenge that has haunted formulators in the past is balancing the in-use
wet strength
requirements with the dispersibility requirements. For example, one can
achieve a high in-use
wet strength in a wet wipe, but the wet wipe may exhibit little or no
dispersibility. In another
example, a wet wipe may exhibit low in-use wet strength, but the wet wipe may
disperse readily.
In one example, a wet wipe may exhibit a high initial wet strength that
deteriorates over time
prior to use as a result of the wet wipe comprising its liquid composition.
For example, the wet
wipe comprising its liquid composition may at the time of packaging exhibit
sufficient wet
strength, but after sitting in the package for sometime, for example 28 days
or longer, the wet
strength of the wet wipe has deteriorated to an unacceptable level for
consumers.
In light of the foregoing, consumers desire a wet wipe that exhibits
sufficient wet strength
during use, even 28 days after the wet wipe has been produced, and a
dispersibility that is better
than known and existing wet wipes.
Accordingly, there is a need for a wet wipe that exhibits novel properties
compared to
known wet wipes.
SUMMARY OF THE INVENTION
The present invention fulfills the need described above by providing a wet
wipe that
exhibits novel properties compared to known wet wipes.
In one example of the present invention, a wet wipe that exhibits a GM
Elongation of
greater than 6.5% as measured according to the GM Elongation Test Method
described herein, is
provided.
In another example of the present invention, a wet wipe that exhibits a GM
Modulus of
less than 2350, is provided.
In still another example of the present invention, a wet wipe that exhibits a
Caliper of
greater than 0.515 as measured according to the Caliper Test Method described
herein, is
provided.
In even another example of the present invention, a wet wipe that exhibits a
Caliper of
less than 0.455 as measured according to the Caliper Test Method described
herein, is provided.
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Accordingly, the present invention provides novel wet wipes comprising a
fibrous
structure and a liquid composition and methods for making same.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a plot of GM Elongation to Caliper (Thickness) for wet wipes of the
present
invention and commercially available wet wipes, illustrating the relatively
high level of GM
Elongation exhibited by the wet wipes of the present invention;
Fig. 2 is a plot of GM Modulus to Caliper (Thickness) for wet wipes of the
present
invention and commercially available wet wipes, illustrating the relatively
low level of GM
Modulus exhibited by the wet wipes of the present invention; and
Fig. 3 is a plot of GM Modulues to GM Elongation for wet wipes of the present
invention
and commercially available wet wipes, illustrating the relatively low level of
GM Modulus
exhibited by the wet wipes of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Definitions
"Fibrous structure" as used herein means a structure that comprises one or
more filaments
and/or fibers. In one example, a fibrous structure according to the present
invention means an
orderly arrangement of filaments and/or fibers within a structure in order to
perform a function.
Non-limiting examples of fibrous structure of the present invention include
paper, fabrics
(including woven, knitted, and non-woven), and absorbent pads (for example for
diapers or
feminine hygiene products).
Non-limiting examples of processes for making fibrous structures include known
wet-laid
papermaking processes, air-laid papermaking processes, and other nonwoven
making processes
such as meltblowing, spunbonding, and carding. Such wet-laid and/or air-laid
papermaking
processes typically include steps of preparing a fiber composition in the form
of a suspension in a
medium, either wet, more specifically aqueous medium, or dry, more
specifically gaseous, i.e.
with air as medium. The aqueous medium used for wet-laid processes is
oftentimes referred to
as a fiber slurry. The fibrous slurry is then used to deposit a plurality of
fibers onto a forming
wire or belt such that an embryonic fibrous structure is formed, after which
drying and/or
bonding the fibers together results in a fibrous structure. Further processing
the fibrous structure
may be carried out such that a wet wipe is formed.
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The fibrous structures of the present invention may be homogeneous or may be
layered.
If layered, the fibrous structures may comprise at least two and/or at least
three and/or at least
four and/or at least five layers.
The fibrous structures of the present invention may be co-formed fibrous
structures.
"Co-formed fibrous structure" as used herein means that the fibrous structure
comprises a
mixture of at least two different materials wherein at least one of the
materials comprises a
filament, such as a polypropylene filament, and at least one other material,
different from the first
material, comprises a solid additive, such as a fiber and/or a particulate. In
one example, a co-
formed fibrous structure comprises solid additives, such as fibers, such as
wood pulp fibers, and
filaments, such as polypropylene filaments.
"Solid additive" as used herein means a fiber and/or a particulate.
"Particulate" as used herein means a granular substance or powder.
"Fiber" and/or "Filament" as used herein means an elongate particulate having
an
apparent length greatly exceeding its apparent width, i.e. a length to
diameter ratio of at least
about 10. In one example, a "fiber" is an elongate particulate as described
above that exhibits a
length of less than 5.08 cm (2 in.) and a "filament" is an elongate
particulate as described above
that exhibits a length of greater than or equal to 5.08 cm (2 in.).
Fibers are typically considered discontinuous in nature. Non-limiting examples
of fibers
include wood pulp fibers and synthetic staple fibers such as polyester fibers.
Filaments are typically considered continuous or substantially continuous in
nature.
Filaments are relatively longer than fibers. Non-limiting examples of
filaments include
meltblown and/or spunbond filaments. Non-limiting examples of materials that
can be spun into
filaments include natural polymers, such as starch, starch derivatives,
cellulose and cellulose
derivatives, hemicellulose, hemicellulose derivatives, and synthetic polymers
including, but not
limited to polyvinyl alcohol filaments and/or polyvinyl alcohol derivative
filaments, and
thermoplastic polymer filaments, such as polyesters, nylons, polyolefins such
as polypropylene
filaments, polyethylene filaments, and biodegradable or compostable
thermoplastic fibers such as
polylactic acid filaments, polyhydroxyalkanoate filaments and polycaprolactone
filaments. The
filaments may be monocomponent or multicomponent, such as bicomponent
filaments.
In one example of the present invention, "fiber" refers to papermaking fibers.
Papermaking fibers useful in the present invention include cellulosic fibers
commonly known as
wood pulp fibers. Applicable wood pulps include chemical pulps, such as Kraft,
sulfite, and
sulfate pulps, as well as mechanical pulps including, for example, groundwood,
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thermomechanical pulp and chemically modified thermomechanical pulp. Chemical
pulps,
however, may be preferred since they impart a superior tactile sense of
softness to tissue sheets
made therefrom. Pulps derived from both deciduous trees (hereinafter, also
referred to as
"hardwood") and coniferous trees (hereinafter, also referred to as "softwood")
may be utilized.
5 The hardwood and softwood fibers can be blended, or alternatively, can be
deposited in layers to
provide a stratified web. U.S. Pat. No. 4,300,981 and U.S. Pat. No. 3,994,771
disclose layering of
hardwood and softwood fibers. Also applicable to the present invention are
fibers derived from
recycled paper, which may contain any or all of the above categories as well
as other non-fibrous
materials such as fillers and adhesives used to facilitate the original
papermaking. Non-limiting
examples of suitable hardwood pulp fibers include eucalyptus and acacia. Non-
limiting
examples of suitable softwood pulp fibers include Southern Softwood Kraft
(SSK) and Northern
Softwood Kraft (NSK).
"Hardwood pulp fiber" as used herein means pulp fibers obtained from deciduous
trees.
Non-limiting examples of deciduous trees include Northern hardwood trees and
tropical
hardwood trees. Non-limiting examples of hardwood pulp fibers include hardwood
pulp fibers
obtained from a fiber source selected from the group consisting of Acacia,
Eucalyptus, Maple,
Oak, Aspen, Birch, Cottonwood, Alder, Ash, Cherry, Elm, Hickory, Poplar, Gum,
Walnut,
Locust, Sycamore, Beech, Catalpa, Sassafras, Gmelina, Albizia, Anthocephalus,
Magnolia, and
mixtures thereof. In one example, the hardwood pulp fiber of the present
invention is obtained
from Eucalyptus.
"Tropical hardwood pulp fiber" as used herein means pulp fibers obtained from
a tropical
hardwood tree. Non-limiting examples of tropical hardwood trees include
Eucalyptus trees
and/or Acacia trees.
In addition to the various wood pulp fibers, other cellulosic fibers such as
cotton linters,
rayon, lyocell and bagasse can be used in this invention. Other sources of
cellulose in the form
of fibers or capable of being spun into fibers include grasses and grain
sources.
In addition, trichomes such as from "lamb's ear" plants and seed hairs can
also be utilized
in the fibrous structures of the present invention.
In one example, the fibrous structure may comprise 100% by weight on a dry
fiber basis
of softwood fibers, such as NSK fibers. In another example, the fibrous
structure may comprise
a mixture of softwood fibers, such as NSK fibers, and hardwood fibers, such as
Eucalyptus
fibers. In still another example, the fibrous structure may comprise less than
100% and/or less
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than 90% and/or less than 80% and/or to about 70% by weight on a dry fiber
basis of softwood
fibers, such as NSK fibers, and greater than 0% and/or greater than 10% and/or
greater than 20%
and/or to about 30% by weight on a dry fiber basis of hardwood fibers, such as
Eucalyptus fibers.
In still another example, the fibrous structure may comprise greater than 0%
and/or
greater than 5% and/or greater than 10% and/or greater than 20% and/or greater
than 30% and/or
to about 50% by weight on a dry fiber basis of fibers, such as pulp fibers,
that exhibit a mean
fiber length of from less than 1 mm and/or less than 0.9 mm and/or less than
0.8 mm and/or to
about 0.5 mm and/or to about 0.6 mm and/or to about 0.7 mm.
"Wet wipe" as used herein means a fibrous structure that contains greater than
20%
and/or greater than 40% and/or greater than 50% and/or greater than 75% by
weight of the wet
wipe of a liquid composition. In one example, the fibrous structure of the
present invention
comprises a % saturation of greater than 50% and/or greater than 75% and/or
greater than 100%
and/or greater than 125% and/or greater than 150% and/or to about 1000% and/or
to about 500%
and/or to about 400% and/or to about 300% and/or to about 250% and/or to about
200%.
The liquid composition may be added to the fibrous structure to form a wet
wipe prior to
and/or after packaging and/or prior to and/or after folding, if any, and/or
prior to and/or after any
post processing operation, such as embossing, tuft generating, printing,
combining with other
fibrous structure plies and mixtures thereof. The wet wipe is typically
packaged in a moisture
impervious container and/or wrapper. The wet wipe may be in the form of one or
more
individual sheets, such as a stack of sheets, which may be interleaved. In
another example, the
wet wipes of the present invention may be in the form of wet wipe rolls. Such
wet wipe rolls
may comprise a plurality of connected, but perforated sheets of fibrous
structure, that are
separably dispensable from adjacent sheets.
The fibrous structure, as described above, may be utilized to form a wet wipe.
"Wet
wipe" may be a general term to describe a piece of material, generally fibrous
structure, used in
cleansing hard surfaces, food, inanimate objects, toys and body parts. In
particular, many
currently available wet wipes may be intended for the cleansing of the
perianal area after
defecation. Other wet wipes may be available for the cleansing of the face or
other body parts.
Multiple wipes may be attached together by any suitable method to form a mitt.
The fibrous structure from which a wet wipe is made should be strong enough to
resist
tearing during normal use, yet still provide softness to the user's skin, such
as a child's tender
skin. Additionally, the fibrous structure should be at least capable of
retaining its form for the
duration of the user's cleansing experience.
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Wet wipes may be generally of sufficient dimension to allow for convenient
handling.
Typically, the wipe may be cut and/or folded to such dimensions as part of the
manufacturing
process. In some instances, the wipe may be cut into individual portions so as
to provide separate
wipes which are often stacked and interleaved in consumer packaging. In other
embodiments, the
wipes may be in a web form where the web has been slit and folded to a
predetermined width and
provided with means (e.g., perforations) to allow individual wipes to be
separated from the web
by a user. Suitably, an individual wipe may have a length between about 100 mm
and about 250
mm and a width between about 140 mm and about 250 mm. In one embodiment, the
wipe may
be about 200 mm long and about 180 mm wide. The material of the wipe may
generally be soft
and flexible, potentially having a structured surface to enhance its cleaning
performance.
The wet wipes may also be treated to improve the softness and texture thereof
by
processes such as hydroentanglement or spunlacing. The wet wipes may be
subjected to various
treatments, such as, but not limited to, physical treatment, such as ring
rolling, as described in
U.S. Patent No. 5,143,679; structural elongation, as described in U.S. Patent
No. 5,518,801;
consolidation, as described in U.S. Patent Nos. 5,914,084, 6,114,263,
6,129,801 and 6,383,431;
stretch aperturing, as described in U.S. Patent Nos. 5,628,097, 5,658,639 and
5,916,661;
differential elongation, as described in WO Publication No. 2003/0028165A1;
and other solid
state formation technologies as described in U.S. Publication No.
2004/0131820A1 and U.S.
Publication No. 2004/0265534A1 and zone activation and the like; chemical
treatment, such as,
but not limited to, rendering part or all of the substrate hydrophobic, and/or
hydrophilic, and the
like; thermal treatment, such as, but not limited to, softening of fibers by
heating, thermal
bonding and the like; and combinations thereof.
The wet wipe may have a basis weight of at least about 40 grams/m2. In one
example, the
wipe may have a basis weight of at least about 45 grams/m2. In another
example, the wet wipe
basis weight may be less than 120 grams/m2. In another example, wet wipe may
have a basis
weight of from about 45 grams/m2 to about 90 grams/m2 and/or from about 50
g/m2 to about 80
g/m2.
In one example of the present invention the surface of wet wipe may be
essentially flat. In
another example of the present invention the surface of the wet wipe may
optionally contain
raised and/or lowered portions. These can be in the form of logos, indicia,
trademarks, geometric
patterns, images of the surfaces that the substrate is intended to clean
(i.e., infant's body, face,
etc.). They may be randomly arranged on the surface of the wipe or be in a
repetitive pattern of
some form.
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In another example of the present invention the wet wipe may be biodegradable.
For
example the wet wipe could be made from a biodegradable material such as a
polyesteramide, or
high wet strength cellulose.
"Liquid composition" as used herein means any liquid including, but not
limited to a pure
liquid such as water, an aqueous composition, a colloid, an emulsion, a
suspension, a solution
and mixtures thereof. The term "aqueous composition" as used herein refers to
a composition
that comprises at least 20% and/or at least 40% and/or at least 50% and/or to
about 98% and/or to
about 95% and/or to about 93% and/or to about 90% by weight water.
In one example, the liquid composition comprises water or another liquid
solvent.
Generally the liquid composition is of sufficiently low viscosity to
impregnate the entire structure
of the fibrous structure. In another example, the liquid composition may be
primarily present on a
surface of the fibrous structure surface and to a lesser extent in the inner
structure of the fibrous
structure. In a further example, the liquid composition is releasably carried
by the fibrous
structure, that is the liquid composition is carried on or in the fibrous
structure and is readily
releasable from the fibrous structure by applying some force to the fibrous
structure, for example
by wiping a surface, such as a human skin, with the fibrous structure.
The liquid composition of the present invention may comprise an oil-in-water
emulsion.
In one example, the liquid composition of the present invention comprises at
least 80% and/or at
least 85% and/or at least 90% and/or at least 95% by weight water.
When present on and/or in the fibrous structure of the present invention, the
liquid
composition may be present at a level of from about 10% to about 1000% of the
basis weight of
the fibrous structure and/or from about 100% to about 700% of the basis weight
of the fibrous
structure and/or from about 200% to about 400% of the basis weight of the
fibrous structure.
The liquid composition may comprise an acid. Non-limiting examples of acids
that can
be used in the liquid composition of the present invention are adipic acid,
tartaric acid, citric acid,
maleic acid, malic acid, succinic acid, glycolic acid, glutaric acid, malonic
acid, salicylic acid,
gluconic acid, polymeric acids, phosphoric acid, carbonic acid, fumaric acid
and phthalic acid
and mixtures thereof. Suitable polymeric acids can include homopolymers,
copolymers and
terpolymers, and may contain at least 30 mole % carboxylic acid groups.
Specific examples of
suitable polymeric acids useful herein include straight-chain poly(acrylic)
acid and its
copolymers, both ionic and nonionic, (e.g., maleic-acrylic, sulfonic-acrylic,
and styrene-acrylic
copolymers), those cross-linked polyacrylic acids having a molecular weight of
less than about
250,000, preferably less than about 100,000 poly (a-hydroxy) acids, poly
(methacrylic) acid, and
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naturally occurring polymeric acids such as carageenic acid, carboxy methyl
cellulose, and
alginic acid. In one example, the liquid composition comprises citric acid
and/or citric acid
derivatives.
The liquid composition may also contain salts of the acid or acids, which may
help to
lower the pH of the liquid composition, or another weak base to impart
buffering properties to
the fibrous structure. The buffering response is due to the equilibrium which
is set up between
the free acid and its salt. This allows the fibrous structure to maintain its
overall pH despite
encountering a relatively high amount of bodily waste as would be found post
urination and/or
defecation in a baby or adult. In one embodiment the acid salt comprises
sodium citrate. The
amount of sodium citrate present in the liquid composition in one example may
be between 0.01
and 2.0%, alternatively 0.1 and 1.25%, or alternatively 0.2 and 0.7% by weight
of the liquid
composition.
In addition to the above ingredients, the liquid composition may comprise
additional
ingredients. Non-limiting examples of additional ingredients that may be
present in the liquid
composition of the present invention include: skin conditioning agents
(emollients, humectants)
including, waxes such as petrolatum, cholesterol and cholesterol derivatives,
di and tri-glycerides
including sunflower oil and sesame oil, silicone oils such as dimethicone
copolyol, caprylyl
glycol and acetoglycerides such as lanolin and its derivatives, emulsifiers;
alcohols;
preservatives; stabilizers; surfactants including anionic, amphoteric,
cationic and non ionic
surfactants, colorants, chelating agents including EDTA, sun screen agents,
solubilizing agents,
perfumes, opacifying agents, vitamins, viscosity modifiers; such as xanthan
gum, astringents and
external analgesics.
In one example, the liquid composition comprises an alcohol, such as
benzylalcohol.
In one example, the liquid composition comprises a perfume.
In one example, the liquid composition comprises a preservative. In another
example, the
liquid composition is void of a preservative.
The liquid composition prior to contacting the fibrous structure of the
present invention
may exhibit a pH of greater than 5 and/or greater than 5.2 and/or greater than
5.5 and/or greater
than 6 and/or less than 10 and/or less than 9 and/or less than 8 and/or less
than 7 as measured
according to the pH Test Method described herein prior to contacting the
fibrous structure.
The pH of the liquid composition may be impacted by the fibrous structure, for
example
the fiber composition of the fibrous structure. The liquid composition may
exhibit a pH of less
than 4.55 and/or less than 4.3 and/or less than 4.1 and/or less than 4 and/or
less than 3.8 and/or
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greater than 2 and/or greater than 2.5 and/or greater than 3 and/or greater
than 3.5 as measured
according to the pH Test Method described herein after being extracted from
the fibrous
structure.
Table 1 below shows the pH of the liquid composition after being extracted
from the
fibrous structure of the present invention and known wet wipes.
Wet Wipe pH of Liquid Composition
Extracted from Wet Wipe
Invention Examplel 4.3
Invention Example 2 4.3
Invention Example 3 4.3
Invention Example 4 4.3
Invention Example 5 4.3
Invention Example 6 4.3
Charmin Freshmates (currently marketed) 4.62
Kleenex Cottonelle Fresh 5.03
Walgreens Flushable Moist Wipes 5.09
Walmart Natural Choice Flushable Moist 5.19
Wipes
Kroger Nice n Soft Flushable Moist Wipes 5.05
Meijer Flushable Moist Wipes 5.23
Target Up&Up Flushable Moist Wipes 5.04
Scott Wipes 5.08
Table 1
In one example, the liquid composition comprises an alcohol. In another
example, the
liquid composition comprises a perfume. In still another example, the liquid
composition
comprises a preservative.
"% Saturation" also equivalently referred to as "saturation loading" as used
herein means
5 the amount of a liquid composition applied to a fibrous structure to form
a wet wipe. In general,
the amount of the liquid composition applied to a fibrous structure according
to the present
invention may be chosen in order to provide maximum benefits to the wet wipe.
Saturation
loading, often expressed as percent saturation, is defined as the percentage
of the dry fibrous
structure' s mass that the liquid composition mass represents. For example, a
saturation load of
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1.0 (equivalently 100% saturation) indicates that the mass of the liquid
composition contained
in/on the fibrous structure is equal to the fibrous structure mass whereas a
saturation load of 1.5
(equivalently 150% saturation) indicates that the mass of the liquid
composition contained in/on
the fibrous structure is 1.5 times the fibrous structure mass.
The wet wipes and/or fibrous structures of the present invention may exhibit a
basis
weight of greater than 15 g/m2 (9.2 lbs/3000 ft2) to about 120 g/m2 (73.8
lbs/3000 ft2) and/or
from about 15 g/m2 (9.2 lbs/3000 ft2) to about 110 g/m2 (67.7 lbs/3000 ft2)
and/or from about 20
g/m2 (12.3 lbs/3000 ft2) to about 100 g/m2 (61.5 lbs/3000 ft2) and/or from
about 30 (18.5
lbs/3000 ft2) to 90 g/m2 (55.4 lbs/3000 ft2). In addition, the wet wipes
and/or fibrous structures
of the present invention may exhibit a basis weight between about 40 g/m2
(24.6 lbs/3000 ft2) to
about 120 g/m2 (73.8 lbs/3000 ft2) and/or from about 50 g/m2 (30.8 lbs/3000
ft2) to about 110
g/m2 (67.7 lbs/3000 ft2) and/or from about 55 g/m2 (33.8 lbs/3000 ft2) to
about 105 g/m2 (64.6
lbs/3000 ft2) and/or from about 60 (36.9 lbs/3000 ft2) to 100 g/m2 (61.5
lbs/3000 ft2).
The wet wipes of the present invention may exhibit an initial total wet
tensile strength of
less than 3000 g/in and/or less than 2500 g/in and/or less than 2000 g/in
and/or less than 1800
g/in and/or less than 1500 g/in and/or less than 1250 g/in and/or greater than
300 g/in and/or
greater than 400 g/in and/or greater than 500 g/in and/or greater than 600
g/in as measured
according to the Wet Tensile Strength Test Method described herein. In one
example, the wet
wipes of the present invention may exhibit a total wet tensile strength after
28 days of less than
2000 g/in and/or less than 1800 g/in and/or less than 1500 g/in and/or less
than 1250 g/in and/or
less than 1000 g/in and/or greater than 100 g/in and/or greater than 200 g/in
and/or greater than
300 g/in and/or greater than 400 g/in as measured according to the Wet Tensile
Strength Test
Method described herein.
The wet wipes of the present invention may exhibit a density (measured at 95
g/in2) of
less than about 0.60 g/cm3 and/or less than about 0.30 g/cm3 and/or less than
about 0.20 g/cm3
and/or less than about 0.10 g/cm3 and/or less than about 0.07 g/cm3 and/or
less than about 0.05
g/cm3 and/or from about 0.01 g/cm3 to about 0.20 g/cm3 and/or from about 0.02
g/cm3 to about
0.10 g/cm3.
The wet wipes of the present invention may be in the form of wet wipe rolls.
Such wet
wipe rolls may comprise a plurality of connected, but perforated sheets of
fibrous structure, that
are separably dispensable from adjacent sheets.
The wet wipes of the present invention may comprises additives such as
softening agents
such as silicones and/or quaternary ammonium compounds, temporary wet strength
agents,
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permanent wet strength agents, bulk softening agents, lotions, silicones,
wetting agents, latexes,
especially surface-pattern-applied latexes, dry strength agents such as
carboxymethylcellulose
and starch, and other types of additives suitable for inclusion in and/or on
wet wipes.
In one example, the wet wipe is void (less than 5% and/or less than 3% and/or
less than
1% and/or less than 0.5% and/or less than 0.1% by weight of the wet wipe) of
any post fibrous
structure making applied polymeric binder.
"Weight average molecular weight" as used herein means the weight average
molecular
weight as determined using gel permeation chromatography according to the
protocol found in
Colloids and Surfaces A. Physico Chemical & Engineering Aspects, Vol. 162,
2000, pg. 107-
121.
"Basis Weight" as used herein is the weight per unit area of a sample reported
in lbs/3000
ft2 or g/m2 and is measured according to the Basis Weight Test Method
described herein.
"Caliper" as used herein means the macroscopic thickness of a fibrous
structure. Caliper
is measured according to the Caliper Test Method described herein.
"Bulk" as used herein is calculated as the quotient of the Caliper, expressed
in microns,
divided by the Basis Weight, expressed in grams per square meter. The
resulting Bulk is
expressed as cubic centimeters per gram. For the products of this invention,
Bulks can be greater
than about 3 cm3/g and/or greater than about 6 cm3/g and/or greater than about
9 cm3/g and/or
greater than about 10.5 cm3/g up to about 30 cm3/g and/or up to about 20
cm3/g. The products of
this invention derive the Bulks referred to above from the basesheet, which is
the sheet produced
by the tissue machine without post treatments such as embossing. Nevertheless,
the basesheets of
this invention can be embossed to produce even greater bulk or aesthetics, if
desired, or they can
remain unembossed. In addition, the basesheets of this invention can be
calendered to improve
smoothness or decrease the Bulk if desired or necessary to meet existing
product specifications.
"Density" as used herein is calculated as the quotient of the Basis Weight
expressed in
grams per square meter divided by the Caliper expressed in microns. The
resulting Density is
expressed as grams per cubic centimeters (g/cm3 or g/cc). In one example, the
Densities can be
greater than 0.05 g/cm3 and/or greater than 0.06 g/cm3 and/or greater than
0.07 g/cm3 and/or less
than 0.10 g/cm3 and/or less than 0.09 g/cm3 and/or less than 0.08 g/cm3. In
one example, a
fibrous structure of the present invention exhibits a density of from about
0.055 g/cm3 to about
0.095 g/cm3.
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"Machine Direction" or "MD" as used herein means the direction parallel to the
flow of
the fibrous structure through the fibrous structure making machine and/or wet
wipe
manufacturing equipment.
"Cross Machine Direction" or "CD" as used herein means the direction parallel
to the
width of the fibrous structure making machine and/or wet wipe manufacturing
equipment and
perpendicular to the machine direction.
"Ply" as used herein means an individual, integral fibrous structure.
"Plies" as used herein means two or more individual, integral fibrous
structures disposed
in a substantially contiguous, face-to-face relationship with one another,
forming a multi-ply
fibrous structure and/or multi-ply wet wipe. It is also contemplated that an
individual, integral
fibrous structure can effectively form a multi-ply fibrous structure, for
example, by being folded
on itself.
"Embossed" as used herein with respect to a fibrous structure means a fibrous
structure
that has been subjected to a process which converts a smooth surfaced fibrous
structure to a
decorative surface by replicating a design on one or more emboss rolls, which
form a nip through
which the fibrous structure passes. Embossed does not include creping,
microcreping, printing or
other processes that may impart a texture and/or decorative pattern to a
fibrous structure.
Fibrous Structure
In one example of the present invention, the fibrous structure of the wet wipe
comprises
greater than 20% and/or greater than 40% and/or greater than 50% and/or
greater than 75%
and/or greater than 90% and/or to about 100% by weight on a total dry fiber
basis of pulp fibers,
such as hardwood and/or softwood pulp fibers.
The fibrous structure may comprise a surface comprising a surface pattern. The
surface
pattern may comprise a non-random, repeating pattern. The surface pattern may
comprise a
formed surface pattern such as resulting from a patterned belt and/or
belt/fabric combination. In
another example, the fibrous structure may be an embossed fibrous structure
that comprises one
or more embossments, such as imparted by passing the fibrous structure (prior
to and/or after
application of a liquid composition) through an embossing nip. The one or more
embossments
may comprise line art embossments and/or dot embossments and/or other non-line
art
embossments.
In one example, the fibrous structure of the present invention may comprise
two or more
regions that are different from one another with respect to their specific
level of wet tensile
strength and/or resistance to disperse.
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A fibrous structure according to the present invention may comprise a surface
comprising
a surface pattern that includes two or more different regions. For example the
fibrous structure
may comprise discrete, high density regions that are surround by a continuous
or substantially
continuous low density region.
In another example of the present invention, the fibrous structure comprises
two or more
regions that exhibit different values of a common intensive property, for
example different
densities (a region of higher density relative to a region of lower density)
and/or different basis
weights.
The fibrous structure may be a creped fibrous structure or an uncreped fibrous
structure.
The fibrous structure may be a fabric and/or belt creped fibrous structure. In
addition, the fibrous
structure may be a wet molded and/or a wet microcontracted fibrous structure.
Further, the
fibrous structure may be a through-air-dried fibrous structure or a
compressively dewatered
fibrous structure, such as a conventional papermaking processed fibrous
structure. In one
example, the fibrous structure is a non-hydroentangled (non-spunlaced) fibrous
structure.
The fibrous structure may comprise a temporary wet strength agent. Suitable
temporary
wet strength agents include materials that can react with hydroxyl groups,
such as on cellulosic
pulp fibers, to form hemiacetal bonds that are reversible in the presence of
excess water. Suitable
temporary wet strength agents are known to those of ordinary skill in the art.
Non-limiting
examples of temporary wet strength agents suitable for the fibrous structures
of the present
invention include glyoxylated polyacrylamide polymers, for example cationic
glyoxylated
polyacrylamide polymers. In one example, the temporary wet strength agent
comprises
Hercobond commercially available from Ashland Inc. In another example, the
temporary wet
strength agent comprises Parez 750 and/or 745 commercially available from
Kemira Chemicals,
Inc.
In one example, the temporary wet strength agent exhibits a pH of less the 7
and/or less
than 6.5 and/or less than 6 and/or less than 5.5 and/or less than 5 and/or
less than 4.5 and/or to
about 2.5 and/or to about 3 and/or to about 3.5. In one example, the pH of the
temporary wet
strength agent is about 4.
Non-limiting examples of temporary wet strength agents made by the methods of
the
present invention generally have weight average molecular weights of from
about 20,000 to
about 400,000 and/or from about 50,000 to about 400,000 and/or from about
70,000 to about
400,000 and/or from about 70,000 to about 300,000 and/or from about 100,000 to
about 200,000.
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The temporary wet strength agents of the present invention impart wet tensile
strength
properties and wet tensile decay properties to the fibrous structures and/or
wet wipes of the
present invention.
It has been found that temporary wet strength agents with high weight average
molecular
5 weights (i.e. those in excess of 300,000) may decay unacceptably slow for
consumer purposes.
Further, it has been found that temporary wet strength agents with extremely
low weight average
molecular weights (i.e. those less than 70,000) may have very low wet strength
and may not be
optimal as temporary wet strength agents for fibrous structures and/or wet
wipes.
Non-limiting examples of temporary wet strength agents in accordance with the
present
10 invention include temporary wet strength agents having the formula:
A
d
Structure I
wherein: A (the moiety present on the co-crosslinking monomeric unit) is
independently an
15 electrophilic moiety, non-limiting examples of which include the
following:
0 0
I I I I
__________________________________ C X __ (R1)¨CH
Z (the moiety present on the reversible, homo-crosslinking monomeric unit) is
independently a
nucleophilic moiety capable of forming an unstable covalent bond with the
electrophilic moiety,
non-limiting examples of which include the following:
0
I I
C X __ (R1)¨CH2OH
and X is independently ¨0¨, ¨NH¨, or ¨NCH3¨; and R1 is a substituted or
unsubstituted aliphatic
group; Y1, Y2, and Y3 are independently ¨H, ¨CH3, or a halogen; Q is a
cationic moiety; and W
is a non-nucleophilic moiety or a nucleophilic moiety that does not form a
stable covalent bond
with the electrophilic moiety. Non-limiting examples of moieties for W include
water-soluble
N,N-dialkyl acrylamide moieties and/or water-soluble carboxylic acid moieties.
The mole percent of a ranges from about 1 % to about 20 %, preferably from
about 2 % to
about 15 %, the mole percent of b ranges from about 0 % to about 60 %,
preferably from about 0
% to about 45 %, the mole percent of c ranges from about 10 % to about 90 %,
preferably from
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about 30 % to about 80 %, and d ranges from about 1 % to about 40 %,
preferably from about 2
% to about 20 %, more preferably from about 5 % to about 12 %.
Unless otherwise expressly specified, values for a, b, c, and d shall be mole
percentage
values based upon the average number of monomeric units in the polymer
backbone of the
temporary wet strength agent of the present invention.
The monomeric units of the polymer backbone of the temporary wet strength
agent of the
present invention may be randomly distributed throughout the polymer in ratios
corresponding to
the mole percentage ranges described herein.
Each class of monomeric units may include a single monomer or may include
combinations of two or more different monomers within that class. The mole
percent of each
monomeric unit within a class of monomeric units may be independently
selected.
In one example, the fibrous structure comprises greater than 5% and/or greater
than 10%
and/or greater than 25% and/or greater than 40% and/or greater than 50% and/or
to about 90%
and/or to about 80% and/or to about 70% by weight of the liquid composition.
Wet Wipe
The fibrous structures of the present invention may be saturation loaded with
a liquid
composition to form a wet wipe. The loading may occur individually, or after
the fibrous
structures are placed in a stack, such as within a liquid impervious container
or packet. In one
example, the fibrous structures may be saturation loaded with from about 1.5 g
to about 6.0 g
and/or from about 2.5 g to about 4.0 g of liquid composition per g of fibrous
structure.
The wet wipes of the present invention may be placed in the interior of a
container, which
may be liquid impervious, such as a plastic tub or a sealable packet, for
storage and eventual sale
to the consumer. The wet wipes may be folded and stacked. The wet wipes of the
present
invention may be folded in any of various known folding patterns, such as C-
folding, Z-folding
and quarter-folding. Use of a Z-fold pattern may enable a folded stack of wet
wipes to be
interleaved with overlapping portions. Alternatively, the wet wipes may
include a continuous
strip of fibrous structure which has perforations between each wet wipe and
which may be
arranged in a stack or wound into a roll for dispensing, one after the other,
from a container,
which may be liquid impervious.
The wet wipes of the present invention may further comprise prints, which may
provide
aesthetic appeal. Non-limiting examples of prints include figures, patterns,
letters, pictures and
combinations thereof.
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In one example, the wet wipe of the present invention exhibits an in-use total
wet tensile
strength of greater than 300 g/in and/or greater than 400 g/in and/or greater
than 500 g/in and/or
greater than 600 g/in and/or less than 2500 g/in and/or less than 2000 g/in
and/or less than 1500
g/in and/or less than 1000 g/in as measured by the Wet Tensile Strength Test
Method described
herein.
In another example, the wet wipe of the present invention exhibits a 12.5 mm
Screen
Retention Value at 3 hours of less than 50% and/or less than 40% and/or less
than 30% and/or
20% and/or less than 15% and/or less than 10% and/or less than 5% as measured
according to the
Shake Flask Test Method described herein.
In another example, the wet wipe of the present invention exhibits a 3 mm
Screen
Retention Value at 3 hours of less than 50% and/or less than 40% and/or less
than 30% and/or
less than 25% and/or less than 20% and/or less than 15% and/or less than 10%
and/or less than
5% as measured according to the Shake Flask Test Method described herein.
Table 2 below shows the GM Elongation, the Caliper and the GM Modulus of
several
invention example wet wipes, and known wet wipes.
Wet Wipe GM Elongation Caliper GM Modulus
% mm
Invention Example 1 8.67 62 1097
0.
Invention Example 2 4.39 45 2165
0.
Invention Example 3 4.85 36 2147
0.
Invention Example 4 8.23 1027
0.59
Invention Example 5 5.39 49 1395
0.
Invention Example 6 8.56 1092
0.50
Charmin Freshmates 6.38 0.46 3091
(currently marketed)
Kleenex Cottonelle 5.52 0.51 3871
Fresh
Walgreens Flushable 6.43 0.48 3583
Moist Wipes
Walmart Natural 6.16 0.46 2963
Choice Flushable
Moist Wipes
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Kroger Nice n Soft 6.12 0.48 2379
Flushable Moist
Wipes
Meijer Flushable 5.74 0.47 2587
Moist Wipes
Target Up&Up 6.07 0.47 3193
Flushable Moist
Wipes
Scott Natural Wipes 5.63 0.50 4038
Table 2
In one example, the wet wipes of the present invention exhibit a GM Elongation
of
greater than 4% and/or greater than 5% and/or greater than 6% and/or greater
than 6.5% and/or
greater than 7% and/or greater than 7.5% and/or greater than 8% and/or greater
than 8.5% and/or
greater than as measured according to the GM Elongation Test Method described
herein.
In another example, the wet wipes of the present invention exhibit a Caliper
(Thickness)
of greater than 0.35 mm and/or greater than 0.45 mm and/or greater than 0.515
mm and/or
greater than 0.52 mm and/or greater than 0.55 mm and/or greater than 0.58 mm
and/or greater
than 0.60 mm as measured according to the Caliper Test Method described
herein.
In still another example, the wet wipes of the present invention exhibit a
Caliper
(Thickness) of less than 0.455 mm and/or less than 0.40 mm as measured
according to the
Caliper Test Method described herein.
In yet another example, the wet wipes of the present invention exhibit a GM
Modulus of
less than 2350 and/or less than 2300 and/or less than 2250 and/or less than
2200 and/or less than
2150 and/or less than 1800 and/or less than 1500 and/or less than 1300 and/or
less than 1100 as
measured according to the GM Modulus Test Method described herein.
Method for Making Fibrous structure
Any suitable process known in the art may be used to make the fibrous
structure of the
present invention. In one example, the fibrous structure of the present
invention is made using a
wet-laid fibrous structure making process.
The fibrous structure of the present invention may be made by any suitable
process
known in the art so long as the fibrous structure meets the wet tensile
strength and/or
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dispersibility requirements described herein. In one example, the fibrous
structure of the present
invention is made using a wet-laid fibrous structure making process.
In one example, a method for making a wet wipe comprising the steps of:
a. providing a fibrous structure, for example a fibrous structure according
to the present
invention; and
b. contacting the fibrous structure with a liquid composition, for example a
fibrous
structure according to the present invention such that a wet wipe, for example
a wet
wipe according to the present invention is produced.
In still another example, a method for making a wet wipe comprising the steps
of:
a. providing a fibrous structure, for example a fibrous structure according to
the present
invention; and
b. contacting the fibrous structure with a liquid composition, for example a
liquid
composition according to the present invention such that the pH of the liquid
composition after being extracted from the fibrous structure is less than 4.55
as
measured according to the pH Test Method to produce a wet wipe, for example a
wet
wipe according to the present invention.
In yet another example, a method for making a wet wipe comprising the steps
of:
a. providing a fibrous slurry comprising a plurality of fibers and a temporary
wet
strength agent; and optionally, a dry strength agent;
b. depositing the fibrous slurry onto a forming wire to form an embryonic web;
c. transferring the embryonic web to a patterned belt to impart a surface
pattern to the
embryonic web;
d. drying the embryonic web to form a fibrous structure, for example a fibrous
structure
according to the present invention; and
e. contacting the fibrous structure with a liquid composition, for example a
liquid
composition according to the present invention to form a wet wipe, for example
a wet
wipe according to the present invention.
In yet another example, a method for making a wet wipe comprising the steps
of:
a. providing a fibrous slurry comprising a plurality of fibers and a temporary
wet
strength agent; and optionally, a dry strength agent;
b. depositing the fibrous slurry onto a forming wire to form an embryonic web;
c. transferring the embryonic web to a patterned belt to impart a surface
pattern to the
embryonic web;
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d. drying the embryonic web to form a fibrous structure, for example a fibrous
structure
according to the present invention; and
e. contacting the fibrous structure with a liquid composition, for example a
liquid
composition according to the present invention to form a wet wipe, for example
a wet
5 wipe
according to the present invention wherein the pH of the liquid composition
after being extracted from the fibrous structure is less than 4.55 as measured
according to the pH Test Method, is provided.
The fibrous structure may be any suitable fibrous structure. In one example,
the fibrous
structure comprises a wet-laid fibrous structure.
10 In
another example, the fibrous structure comprises greater than 75% and/or
greater than
80% and/or greater than 90% and/or greater than 95% and/or to about 100% by
weight of pulp
fibers.
The patterned belt of the present invention may be a molding member. A
"molding
member" is a structural element that can be used as a support for an embryonic
web comprising a
15 plurality of cellulosic fibers and a plurality of synthetic fibers, as
well as a forming unit to form,
or "mold," a desired microscopical geometry of the wet wipe of the present
invention. The
molding member may comprise any element that has fluid-permeable areas and the
ability to
impart a microscopical three-dimensional pattern to the structure being
produced thereon, and
includes, without limitation, single-layer and multi-layer structures
comprising a stationary plate,
20 a belt, a woven fabric (including Jacquard-type and the like woven
patterns), a band, and a roll.
In one example, the molding member is a deflection member. The molding member
may
comprise a surface pattern according to the present invention that is imparted
to the wet wipe
during the wet wipe making process.
A "reinforcing element" is a desirable (but not necessary) element in some
embodiments
of the molding member, serving primarily to provide or facilitate integrity,
stability, and
durability of the molding member comprising, for example, a resinous material.
The reinforcing
element can be fluid-permeable or partially fluid-permeable, may have a
variety of embodiments
and weave patterns, and may comprise a variety of materials, such as, for
example, a plurality of
interwoven yarns (including Jacquard-type and the like woven patterns), a
felt, a plastic, other
suitable synthetic material, or any combination thereof.
In one example of a method for making a wet wipe of the present invention, the
method
comprises the step of contacting an embryonic fibrous web with a deflection
member (molding
member) such that at least one portion of the embryonic fibrous web is
deflected out-of-plane of
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another portion of the embryonic fibrous web. The phrase "out-of-plane" as
used herein means
that the wet wipe comprises a protuberance, such as a dome, or a cavity that
extends away from
the plane of the wet wipe. The molding member may comprise a through-air-
drying fabric
having its filaments arranged to produce linear elements within the wet wipes
of the present
invention and/or the through-air-drying fabric or equivalent may comprise a
resinous framework
that defines deflection conduits that allow portions of the wet wipe to
deflect into the conduits
thus forming linear elements within the wet wipes of the present invention. In
addition, a
forming wire, such as a foraminous member may be arranged such that linear
elements within the
wet wipes of the present invention are formed and/or like the through-air-
drying fabric, the
foraminous member may comprise a resinous framework that defines deflection
conduits that
allow portions of the wet wipe to deflect into the conduits thus forming
linear elements within the
wet wipes of the present invention.
The step of contacting the fibrous structure with a liquid composition may
comprise
spraying, dipping, extruding, and/or printing the liquid composition onto the
fibrous structure.
In one example, the liquid composition exhibits a pH of greater than 5 and/or
greater than
5.2 and/or greater than 5.5 and/or greater than 6 and/or less than 10 and/or
less than 9 and/or less
than 8 and/or less than 7 as measured according to the pH Test Method
described herein prior to
contacting the fibrous structure.
The liquid composition may exhibit a pH of less than 4.55 and/or less than 4.3
and/or less
than 4.1 and/or less than 4 and/or less than 3.8 and/or greater than 2 and/or
greater than 2.5
and/or greater than 3 and/or greater than 3.5 as measured according to the pH
Test Method
described herein after being extracted from the fibrous structure.
In one example, the liquid composition comprises an alcohol. In another
example, the
liquid composition comprises a perfume. In still another example, the liquid
composition
comprises a preservative.
Any suitable level of the liquid composition may be delivered to the fibrous
structure. In
one example, the fibrous structure comprises greater than 5% and/or greater
than 10% and/or
greater than 25% and/or greater than 40% and/or greater than 50% and/or to
about 90% and/or to
about 80% and/or to about 70% by weight of the liquid composition.
Any suitable level of the temporary wet strength agent may be added to the
fibrous slurry.
In one example, the temporary wet strength agent is added to the fibrous
slurry at a level of
greater than 0.1 and/or greater than 0.5 and/or greater than 1 and/or greater
than 3 and/or greater
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than 5 and/or greater than 6 and/or to less than 12 and/or less than 10 and/or
less than 8
pounds/ton of fiber.
Before or after the contacting step, the fibrous structure may converted into
a wet wipe.
The fibrous structure may be in a roll form, such as a parent roll from the
fibrous structure
making process. A roll of fibrous structure may be converted into rolls of wet
wipes and/or
individual sheets of wet wipes.
In one example a roll of fibrous structure may be unwound and slit into
smaller widths of
fibrous structures that may then be wound into smaller width rolls, for
example 188 mm width
rolls.
The rolls of fibrous structure may be loaded into a converting line's unwind
stand. The
unwind stand may be a center driven unwind stand capable of controlling the
tension via speed
control through a series of dancers. In one example, the line speed at this
stage in the converting
line is about 34 m/min. The fibrous structure then may pass over the dancers
and a tensiometer
device that monitors tension of the fibrous structure inline while being
converted with real time
feedback to the center drive unwind stand to control in process tension
monitoring and control.
In one example, the inline converting tension of the fibrous structure may be
about 1 N.
The fibrous structure may then pass over a liquid composition bar (also
referred to as a
lotion bar) with minimal contact such that the lotion bar delivers the liquid
composition through
openings in the lotion bar to a surface of the fibrous structure.
The fibrous structure may then be folded into any suitable fold configuration,
such as a Z-
fold. This folding step may occur prior to the fibrous structure passing over
the liquid
composition bar.
In one example, the folded fibrous structure may be cut to desired dimensions
to form
individual wet wipes. A plurality of the individual wet wipes may be stacked
together and then
packaged in a container and/or wrapper.
In another example, the folded fibrous structure may be perforated and then
wound into a
roll of perforated wet wipes, which may be dispensed from the roll as
individual wet wipes upon
tearing along a perforation.
A container and/or wrapper containing a stack of wet wipes or a roll of wet
wipes forms
an article of manufacture that may be sold to consumers.
In one example, the fibrous structure making process may be directly coupled
or close
coupled to the converting line.
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In another example, the fibrous structure making process may comprise slitting
the
fibrous structure prior to moving to the converting line.
Non-limiting Example
One example of a process for making a wet wipe is as follows. A wet wipe in
accordance
with the present invention is prepared using a fibrous structure made by a
fibrous structure
making machine having a non-layered headbox.
A conventional pulper is used to prepare the hardwood stock chest with
eucalyptus fiber
having a consistency of about 3.0% by weight to form a thick stock.
Separately, a conventional
pulper is used to prepare the softwood stock chest with northern softwood
kraft (NS K) fiber
having a consistency of about 3.0% by weight to form a thick stock. The NSK
fiber is passed
through a refiner and is refined to a Canadian Standard Freeness (CSF) of
about 650. After
refining, a temporary wet strength agent, Hercules Hercobond 1194 at 1%
solids, is added to the
NSK thick stock at a rate of about 6.1 pounds per ton of fiber. The refined
NSK thick stock and
the Eucalyptus thick stock are then combined into a common stock line at an in-
line mixer to
form a homogeneous thick stock at a proportion of 70% NSK and 30% Eucalyptus.
The homogeneous thick stock is pumped to the fan pump where it is diluted from
about
3% consistency to about 0.1% to about 0.2% consistency with process water
having a pH of
about 5.2 to about 5.5. Once diluted, the homogeneous slurry is pumped to the
headbox where
the fiber slurry is evenly distributed onto a forming wire (84x78, Albany
International) traveling
at a velocity of 220 feet per minute to form an embryonic web. The vacuum
slots located on the
wire table vacuum are used to dewater the embryonic web to a consistency of
about 20% to about
25% before entering the wire-to-press transfer zone.
A pickup shoe is used to transfer the embryonic web from the forming wire to a
patterned
drying belt. The speed of the patterned drying belt is about 200 feet per
minute. The drying belt is
designed to mold a pattern of substantially discrete high density regions
surrounded by a
continuous network of low density regions into the embryonic web. The drying
belt is formed by
casting an impervious resin surface onto a fiber mesh supporting fabric. The
supporting fabric is
a 98x62 filament, dual layer mesh. The thickness of the resin cast is about 22
mils above the
supporting fabric.
While remaining in contact with the patterned drying belt, the web is pre-
dried by air
blow-through pre-dryers to a fiber consistency of about 60% by weight.
After the pre-dryers, the semi-dry web is transferred to the Yankee dryer via
pressure roll
nip and adhered to the surface of the Yankee dryer with a sprayed a creping
adhesive coating.
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The creping adhesive is an aqueous dispersion with the actives consisting of
Georgia Pacific's
Unicrepe 457T20 and Vinylon Works' Vinylon 8844 at a blend of about 25% / 75%,
respectively. The fiber consistency is increased to about 97% before the web
is dry-creped from
the Yankee with a doctor blade.
The doctor blade has a bevel angle of about 45 degrees and is positioned with
respect to
the Yankee dryer to provide an impact angle of about 101 degrees. The Yankee
dryer is operated
at a temperature of about 350 F (177 C) and a speed of about 200 feet per
minute. The fibrous
structure is wound into a parent roll using a surface driven reel drum having
a surface speed of
about 191 feet per minute.
The parent roll width is slit to a width of 188 millimeters as it rewound into
a "chip" roll.
The "chip" is placed onto the unwind stand and the fibrous web is threaded
through a wet wipe
converting line. The speed of the fibrous web through the process is 34 meters
per minute while
the fibrous web tension is controlled to about 1 Newton. The fibrous web then
passes over a
lotion bar (liquid composition bar) where the fibrous web absorbs the lotion
(liquid composition)
at a saturation level of about 150% to about 200%.
The lotion-saturated fibrous web is then folded in a Z-fold configuration
(ribbon), cut to
length, stacked, and optionally interleaved to form a stack of wet wipes,
which then are placed
into a wrapper or container, such as a tub.
TEST METHODS
Unless otherwise indicated, all tests described herein including those
described under the
Definitions section and the following test methods are conducted on samples
that have been
conditioned in a conditioned room at a temperature of 23 C 2.2 C and a
relative humidity of
50% 10% for 2 hours prior to the test. All tests are conducted in such
conditioned room.
pH Test Method
In order to measure the pH of a liquid composition present on a wet wipe, the
following
procedure is used. First, secure a C-clamp's frame in the jaws of a 6 inch
table vise. Tighten the
table vise so that the C-clamp does not move. The C-clamp should not shift
within the table vise
as compression is formed between the stationary foot and the adjustable foot
of the C-clamp.
The feet of the C-clamp have a 1 inch diameter.
Calibrate a digital pH meter (Oakton pH 5, Acorn Series, WD-35613-00 or
equivalent)
according to the manufacturer's instruction manual. Measurements are made
according to the
manufacturer's instruction manual.
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Wearing latex or rubber gloves, dispense a single sheet of wet wipe from a
package or tub
of wet wipes being sure that the wet wipe has not dried out too much. Fold the
single wet wipe
sheet five times (resulting in a 32-p1y implement).
Place the folded wet wipe sheet onto the stationary foot of the C-clamp. Turn
the
5 adjustment screw for the adjustable foot of the C-clamp until the
stationary and adjustable foot of
the C-clamp contact the folded wet wipe sheet.
Position a 50 ml beaker under the folded wet wipe sheet and then turn the
adjustment
screw of the C-clamp to begin compressing the folded wet wipe sheet to cause
the liquid
composition to flow from the folded wet wipe sheet and collect the liquid
composition into the 50
10 ml beaker.
Repeat the steps of this procedure with additional wet wipes from the package
or tub until
the level of extricated liquid composition in the 50 ml beaker is sufficient
for measuring pH per
the pH meter manufacturer's instruction manual.
Measure and record the resulting pH for the wet wipe.
15 One of ordinary skill in the art will understand how to measure the pH
of a liquid
composition prior to contacting a fibrous structure and/or a temporary wet
strength agent.
Shake Flask Test Method
To determine the dispersibility of a wet wipe, the following Shake Flask Test
is
performed. The results of this test show the Screen Retention Value of a wet
wipe at various size
20 screens.
Sample Preparation: Weigh a wet wipe to be tested. Incubate a wet wipe sample
in a
2800 mL baffled Fernbach flask with tap water on a rotary shaker at 150 rpm.
After 3 hours the
contents of the flask is passed through a sequential series of different sized
perforated plates with
openings of 12.5 mm, 6 mm, 3 mm, and 1.5 mm. Material retained on each plate
is recovered,
25 dried at 40 C, and weighed. The percent of material retained is
calculated based on the initial
weight of the wet wipe. The overall loss of the wet wipe is also calculated.
Basis Weight Test Method
Basis weight of a fibrous structure and/or wet wipe sample is measured by
selecting
twelve (12) usable units (also referred to as sheets) of the fibrous structure
and/or wet wipe and
making two stacks of six (6) usable units each. Perforation, if any, must be
aligned on the same
side when stacking the usable units. A precision cutter is used to cut each
stack into exactly 8.89
cm x 8.89 cm (3.5 in. x 3.5 in.) squares. The two stacks of cut squares are
combined to make a
basis weight pad of twelve (12) squares thick. The basis weight pad is then
weighed on a top
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loading balance with a minimum resolution of 0.01 g. The top loading balance
must be protected
from air drafts and other disturbances using a draft shield. Weights are
recorded when the
readings on the top loading balance become constant. The Basis Weight is
calculated as follows:
Basis Weight = Weight of basis weight pad (g) x 3000 ft2
(lbs/3000 ft2) 453.6 g/lbs x 12 (usable units) x 1L12.25 in2 (Area of basis
weight pad)/144 in21
Basis Weight = Weight of basis weight pad (g) x 10,000 cm2/m2
(g/m2) 79.0321 cm2 (Area of basis weight pad) x 12 (usable units)
Caliper Test Method
To measure the caliper (thickness) of a wet wipe, the following procedure is
used.
Identify a minimum of 5 different locations on the wet wipe to measure the
caliper. Cut the 5 or
more portions (replicates) in a dimension greater than the foot of the Caliper
Tester (Ono Sokki
GS ¨ 503 Linear Gauge Sensor with an Ono Sokki DG3610 display or equivalent.
May be
obtained from Measure-All, Inc. 447 Nilles Road, Fairfield, OH 45014). to
contact the sample.
When testing finished wet wipe product, open a package of wet wipes and
randomly select 5
finished wet wipe products and measure immediately in their normal wet state.
Place package
with remaining product in a resealable plastic bag and seal.
Before using the Caliper Tester, make sure that the pressure foot (a stainless
steel circular
foot Area: 2500 mm2 50mm2 (56 mm Diameter) and Foot Pressure: 0.501kPa
0.021) and anvil
surfaces are clean, that the calibration of the instrument has been done per
the manufacturer' s
instruction manual, and that the instrument is mounted on a solid level
surface free from
noticeable vibration, for example a granite base with mounting arm (Chicago
Dial Indicator Co.
Part No. 608-12-1R or equivalent), which may be obtained from Measure-All,
Inc. 447 Nilles
Road, Fairfield, OH 45014. Calibration should include verification of 0.50
lkPa 0.021
(0.073PSI 0.003) pressure with a balance, verification that the presser foot
is level to the base I
0.05 mm, and readings of steel gauge blocks accurate to I 0.05mm. Zero the
thickness gauge as
described by the manufacturer.
With the Caliper Tester foot in the up-position, center the sample portion
underneath.
Lower the foot with the handle at a rate of approximately 3mm per second.
After the foot
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contacts the sample, wait 5 seconds and record the caliper (thickness) result
for each sample
portion (replicate).
1) Calculate the Mean for replicates used for measured sample.
2) Report Thickness in mm to the nearest 0.01 mm.
Do not use sample portions cut with a die. Do not make thickness readings on
creases
resulting from folds. Do not make thickness readings on samples with obvious
defects such as
wrinkles, tears, and holes. Do not handle in areas to be measured. Do not test
the same area of a
sample portion more than once.
Elongation, Tensile Strength, TEA and Modulus Test Methods
To test wet wipes, open a package of wet wipes and remove 8 wet wipes. Place
the
opened package of wet wipes in a resealable plastic bag and seal. Using a 50
mm wide by 500
mm long precision sample cutter (JDC-50M-12, Thwing-Albert Instrument Company
10960
Dutton Road Philadelphia, PA) cut 4 replicates of each sample in the MD and CD
directions to a
length greater than 250mm. If sample available does not allow for the greater
than 250 mm
length report the length as a deviation and set the instrument gage length
accordingly (see
Instrument Settings). The sample should be gripped by at least 25mm at each
end. For finished
product wipes, test samples immediately. Cut samples for their unfolded
position whenever
possible. The total wet tensile strength of a wet wipe is measured by this
procedure also.
a. Testing Apparatus
Tensile Tester to be used and settings are as follows:
- Tensile Tester Constant Rate of Elongation (CRE) Tensile Tester, capable
of performing
the test profile as described. Recommended Thwing-Albert Instruments:
EJA Vantage (preferred), EJA, or Intelect II STD Tensile Testers from
Thwing-Albert Instrument Company, 10960 Dutton Road Philadelphia,
PA 19154 USA (215) 637-0100. Recommended MTS Instruments:
MTS Synergie 200/L, MTS Alliance RT/1 Tensile Testers from MTS
1001 Sheldon Drive, Cary, NC 27513, or equivalent. Refer to Analytical Method
GCAS
58007265 "Testing and Calibration of Instruments ¨ The Tensile Tester".
- Tensile Tester Load Cell - Cell should be chosen such that the normally
measured force
is between 20% and 95% of the range in use. Obtain from Tensile Tester
Manufacturer.
- Calibration Weights - Refer to Tensile Tester Manufacturer.
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- Tensile Tester Grips Flat face, air operated, at least 50 mm wide purchased
via the
manufacturer of the tensile tester.
b. Instrument Settings
1. For MTS Instruments set the tensile tester to the following parameters:
(For Thwing-Albert see Section 2 under "Instrument Settings" for all others
instruments check
with the manufacturer for equivalent instrument/software set up.)
- ....................... Test Speed 100 mm/min + 2 mm/min
- ....................... Gauge Length 200 mm most preferred (EDANA)-- or
50mm acceptable if sample
size requires a shorter gauge length, as long as such deviation is reported.
.................. - Slack Compensation .A) 0.10N most preferred B) Non-use
of slack compensation is
acceptable only on instruments that do not have slack compensation
functionality¨such
deviation must be reported.
- ............................. Pre-test Path (no data) None
- ............................. Test path (data collected) "Go Forever
Until Break"
........................ - Post-test Path (no data) None
- ....................... Break Detection 95% drop from Peak
- Break Threshold 0 25N (break detection inactive
until this force is reached)
- ....................... Data Acquisition Rate 100Hz
- ...................... Measured Variables .Tensile Strength (Peak Force)
and Load at 5% Elongation¨reported
in Newtons to 1 decimal place (i.e. 33.5). Additionally, report % Elongation
at Peak % of
adjusted gauge length to 2 decimal places (i.e. 10.44%).
2. For Thwing-Albert Instruments with APS Software set the tensile tester to
the following
parameters:
................................ Test Units -- Elongation Units mms
Test Units -- Curve Units ............. load/elongation %
Test Units -- Load Units .............. N
Set Mode .............................. Tension
Test Over ............................. Fail
................................ Set Range 100%
At Test End ........................... Return
Speeds -- Pre-Test .................... 100.000 mms/min
Speeds -- At Start of Test ............ 100.000 mms/min
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Speeds -- For a distance of ............ 1.000 mms
Speeds -- Then crosshead will travel at .. 100.000 mms/min
Speeds ¨ Return ........................ 1015.998 mms/min
Sample Rate ............................ 100 readings/sec
.................................. Collision Yes
Gauge Length ................................................................
200 mm most preferred (EDANA)-- 50mm
acceptable if sample size requires a shorter gauge length, as long as such
deviation is reported.
Adj. GL ................................ Adjusted
Break Sensitivity ...................... 2 N
................................ Pre-tension . 0.10 N
Load Divider ........................... 1
Sample shape/size -- Sample Shape ...... Rectangular
Sample shape/size ¨ Width .............. 50.000 mms
Sample shape/size ¨ Thickness .......... 10.000 mms
Tag Results - El Trp Load:
Load Units ............................. N
Add'l Parameters ....................... 5.000%
Tag Results - Tangent Modulus:
Elong. Units ........................... cm
................................. Load Units grams
Add'l Parameters ....................... Load
Load Trap gms .......................... 75.000
Measured Variables Tensile Strength (Peak Force) and Load at5%
Elongation--reported in Newtons to ldecimal place (i.e. 33.5). Additionally,
report % Elongation
at Peak in % of adjusted gauge length to 2 decimal places (i.e. 10.44%). Also
in this test set up
Tangent Modulus @ 15gm/cm is shown and may be additionally reported if
desired.
Check tensile tester calibration according to manufacturer's instructions.
Check the load
cell for zero reading and adjust if necessary. Clamp the sample in the grips
of the tensile tester,
mounting the sample without any pretension (<0.05N). Begin the test by
depressing the start
(i.e., test) button. When the test is complete, record the values,
remove the tested sample from the grips and discard. Check the load cell for
zero reading and
repeat this procedure until all samples are tested. Discard the results of any
sample where the
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sample 1) slips during the test, 2) the break occurs in or at either grip or
3) where any break
reaches the grips.
c. Calculations
Record each of the following variables for each replicate:
5 - Peak Load (in Newtons to the nearest 0.1).
- Load at 5% Elongation (in Newtons to the nearest 0.1).-- this quantity is
not specifically
mentioned by EDANA 20.2-89, but it a useful measure for process -development.
- %Elongation at Peak -- EDANA 20.2-89 states to measure % Elongation at
break, but
"break" is not clearly defined by EDANA (i.e. 50% drop from peak, 75% drop,
95% drop?).
10 Additionally, these samples often fail in different ways leading to
highly variable elongation data
(if "break" is defined as complete failure of the sample). This method
measures % Elongation at
Peak.Option for Thwing-Albert Instruments:
- Tangent Modulus @ 15g/cm.
Any of the units can be converted to other units for example g/in for tensile
by appropriate
15 conversion factors known in the art.
d. Reporting Results
Report mean and standard deviation for each measured quantity expressed in N
(Newtons) and report any deviation (i.e. shorter gauge length due to short
sample length, no slack
compensation available, etc). Report the number of replicates used for
testing.
20 The dimensions and values disclosed herein are not to be understood as
being strictly
limited to the exact numerical values recited. Instead, unless otherwise
specified, each such
dimension is intended to mean both the recited value and a functionally
equivalent range
surrounding that value. For example, a dimension disclosed as "40 mm" is
intended to mean
"about 40 mm."
25 The citation of any document, including any cross referenced or related
patent or
application, is not an admission that it is prior art with respect to any
invention disclosed or
claimed herein or that it alone, or in any combination with any other
reference or references,
teaches, suggests or discloses any such invention. Further, to the extent that
any meaning or
definition of a term in this document conflicts with any meaning or definition
of the same term in
30 a document cited herein, the meaning or definition assigned to that term
in this document shall
govern.
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31
While particular embodiments of the present invention have been illustrated
and
described, it would be obvious to those skilled in the art that various other
changes and
modifications can be made without departing from the invention described
herein.
